Method of and apparatus for automatically controlling the speed at which an original and copying material pass through a copying machine

ABSTRACT

This invention relates to an electronic method of automatically controlling the speed of a motor used to pass an original and copying material, on which an image of said original is to be produced, through the exposure zone of a copying machine, successive originals continuously passing through the machine in a manner such that a succeeding original gives rise to a speeddetermining signal before a preceding original has left the exposure zone, which comprises storing a signal until the preceding original has left the exposure zone, interrogating the said signal for the purpose of controlling the speed of the motor for the period during which the said succeeding original is passed through the exposure zone, and cancelling the interrogated signal. This invention also relates to an apparatus for performing the method.

United States Patent Dennhardt et al.

[ METHOD OF AND APPARATUS FOR AUTOMATICALLY CONTROLLING THE SPEED ATWHICH AN ORIGINAL AND COPYING MATERIAL PASS THROUGH A COPYING MACHINE[75] Inventors: Werner Dennhardt, Bleidenstadt;

' Herbert Schroter, Hahn/Taunus,

both of Germany [73] Assignee: Kalle Aktiengesellschaft,

Wiesbaden-Biebrich, Germany [22] Filed: Apr. 20, 1972 [21] Appl. No.:245,713

[30] Foreign Application Priority Data Apr. 22, 1971 Germany P 21 19373.7

[52] U.S. Cl. 355/68, 355/83 [51] Int. Cl. G03b 27/72 [58] Field ofSearch 355/68, 83

[56] References Cited UNITED STATES PATENTS 3,642,377 2/1972 Young355/83 [451 Dec. 11, 1973 Primary ExaminerJohn M. Horan Attorney-JamesE. Bryan [57] ABSTRACT This invention relates to an electronic method ofautomatically controlling the speed of a motor used to pass an originaland copying material, on which an image of said original is to beproduced, through the exposure zone of a copying machine, successiveoriginals continuously passing through the machine in a manner such thata succeeding original gives rise to a speeddetermining signal before apreceding original has left the exposure zone, which comprises storing asignal until the preceding original has left the exposure zone,interrogating the said signal for the purpose of controlling the speedof the motor for the period during which the said succeeding original ispassed through the exposure zone, and cancelling the interrogatedsignal. This invention also relates to an apparatus for performing themethod.

24 Claims, 5 Drawing Figures rnmecnou 0F INCIDENT LIGHT 9:11am 85 I I EEras/e 8e I 2| 1 0 v v v v Io'e 2o REGULATOR I n; I '-sroRAeE MEANS 19 lI AMPLIFIER .l ..L1 fi n. 1 REVERSINGUMT HMPDELAY |5O\STEP-BY-STEP '5STEP-BY-STEP STEP-BY-STEP RIGHHEH UNIT MEASLRINGSYST MEASlRING SYSTEM(STORAGE) (INTERROGATION) (CANCELLATION) 14o I4b- 146 l ELECTRO mcswrrcH ELECTRONIC SWlTGl ELECTRONIC SWITCH,

S2 53 LEFT se LEFT sa LEFT s4 RIGHT s7 RIGHT U i s9 mm PATENTEUUEEI I1973* SHEUZWS DIRECTION OFv FEED Roll 6 PATENTED 1 METHOD OF ANDAPPARATUS FOR AUTOMATICALLY CONTROLLING THE SPEED AT WHICH AN ORIGINALAND COPYING MATERIAL PASS THROUGH A COPYING MACHINE This inventionrelates to a method of and apparatus for automatically controlling thespeed at which an original and copying material pass through a copyingmachine.

Since the translucency of different originals and the sensitivity ofcopying materials fluctuate within wide limits, the speed of travel ofan original and of copying material through the copying station of acopying machine must be varied correspondingly. In conventional copyingmachines, the operator alters the speed of travel by hand and this oftenleads to incorrect settings.

Apparatus thereof has been developed in which the translucency of theoriginals is measured with the aid of a photosensitive measuring unit,and the speed of revolution of the driving motor is adjusted inaccordance with the translucency measured (see German Patent No. 925,751and German Gebrauchsmuster No. 1,977,688).

German Patent No. 1,522,790, as laid open, discloses an apparatus forautomatically controlling the speed of travel of an original and ofcopying material through a copying machine, in which apparatus thetranslucency of the original is measured with the aid ofa CdSphotoresistor, the resistance of which determines the potential of acapacitor, which stores the potential, so that during the copying of anoriginal, a constant speed of travel equal to that determined, ismaintained. With this apparatus, however, a second original can be fedin and its translucency measured only after the first original has beencopied, and this leads to loss of time in the copying operations.

The present invention provides an electronic method of automaticallycontrolling the speed of a motor used to pass an original and copyingmaterial, on which an image of the original is to be produced, throughthe exposure zone of a copying machine, successive originalscontinuously passing through the machine in a manner such that asucceeding original gives rise to a speeddetermining signal before aprecedingoriginal has left the exposure zone, in which method such asignal is stored until the preceding original has left the exposurezone, whereupon the signal is interrogated for the purpose ofcontrolling the speed of the motor for the period during which thesucceeding original is passed through the exposure zone, theinterrogated signal being cancelled. The speed-determining signal may beobtained by measuring the translucency of the succeeding original.

Thus, originalscan be fed successively into the copying machine withoutloss of time, the signals measured on the basis of their translucencycan be stored, and these signals can be interrogated and used forcontrolling the speed of the motor when the corresponding originalsreach the copying station.

The method of the invention is suitable both for copying machines inwhich the copying material is supplied in the form of sheets and forsuch machines in which the copyin'gmaterial is in the form of acontinuous web supplied from one or more rolls, from which the copyingmaterial is automatically drawn and cut to suit the length and width ofthe original to be copied.

The invention also provides an apparatus for automatically controllingthe speed at which a succeeding original and copying material passthrough the copying zone of a continuously operable copying machinehaving a motor drive for originals and copying material, the apparatuscomprising, successively disposed in the path of travel of the originalupstream of the copying zone:

at least one photosensitive measuring unit, arranged to measure thetranslucency of the original,

at least one first switching element which is adapted for actuation bythe leading edge of the original and which when so actuated:

a. switches on a first step-by-step switching and b. connects thephotosensitive measuring unit to a storage unit for a period dependingon the measured translucency by way of the first step-by-step switchingsystem whereby the signal derived from said measuring unit is stored,

at least one second switching element which is adapted for actuation bythe leading edge of the original and which when so actuated switches ona second step-by-step switching system whereby the stored signal ispassed through an amplifier to a device for controlling the speed of themotor during the passage of the original and copying material throughthe copying zone, and

at least one third switching element which is adapted for actuation bythe leading edge of the original and which when so actuated switches ona third step-by-step switching mechanism, whereby a stored signalrelating to the preceding original is cancelled.

The invention further provides an apparatus for automaticallycontrolling the speed at which an original and copying material passthrough'the copying zone of a copying machine having a motor drive forthe original and the copying material, the apparatus comprising,successively disposed in the path of travel of the original upstream ofthe copying zone: I

at least one photosensitive measuring unit, arranged to measure thetranslucency of the original,

at least one first switching element which is adapted for actuation bythe leading edge of the original and which when so actuated:

a. switches on a first step-by-step switching system and b. connects thephotosensitive measuring unit to a storage unit for a period dependingon the measured translucency by way of the first step-by-step switchingsystem, whereby the signal derived from the measuring unit is stored,

at least one second switching element which is adapted for actuation bythe leading edge of the original and which when so actuated switches ona second step-by-step switching system whereby the stored signal ispassed through an amplifier to a device for controlling the speed of themotor during system the passage of the original and the copying materialthrough the copying zone, and further comprising a third switchingelement disposed in the path of travel of the original downstream of thecopying zone, which switching element is adapted for actuation by thetrailing edge of the original and which when so actuated switches on athird step-by-step switching system whereby the stored signal iscancelled.

The invention still further provides an apparatus for automaticallycontrolling the speed at which a succeeding original and copyingmaterial pass through the copying zone of a continuously operablecopying machine having a motor drive for originals and copying material,the apparatus comprising, successively disposed in the path of travel ofthe original upstream of the copying zone:

at least one photosensitive measuring unit; arranged to measure thetranslucency of the original,

at least one first switching element which is adapted for actuation bythe leading edge of the original and when so actuated:

a. switches on a first step-by-step switching system and b. connects thephotosensitive measuring unit to a storage unit for a period dependingon the measured translucency by way of the first step-by-step switchingsystem whereby the signal derived from the measuring unit is stored,

at least one second switching element which is adapted for actuation bythe leading edge of the original and which when so actuated switches ona second step-by-step switching system whereby a. the stored signal ispassed through an amplifier to a device for controlling the speed of themotor during the passage of the original and copying material throughthe copying zone and b. a stored signal relating to the precedingoriginal is cancelled.

The photosensitive measuring unit for measuring the translucency of theoriginal preferably comprises a plurality of photosensitive elementswhich are relatively small in order to increase the likelihood of thetranslucency of any part of the original that carries no written matterbeing measured. For the same reason, it is advantageous so to arrangethe photosensitive elements that they are staggered with respect to oneanother both parallel to and at right angles to the direction in whichthe original moves. If the photosensitive measuring unit comprises aplurality of photosensitive elements, then a discriminator is connectedbetween the photosensitive elements and the storage elements, whichdiscriminator seeks out from among the signals measured at thephotosensitive elements that signal corresponding to the greatesttranslucency. Photo resistors. photoelectric cells and the like can beused in known manner as the photosensitive elements.

In copying machines in which webs of copying material having differentproperties are stored and one of the webs is selected on the basis ofthe measured properties of the original, one photosensitive measuringunit is sufficient if the originals are always introduced on the sameguide strip, i.e. on the same side, of a feed table. If however, theoriginals are introduced on the righthand or left-hand guide strip ofthe feed table, depending upon their width, at least two photosensitivemeasuring units are present. The same applies in the case of copyingmachines in which a plurality of stacks of sheet copying material havingdifferent properties are stored.

The switching elements, disposed in the path of travel of the originalupstream of the copying station, may be mechanical switches, such as forexample microswitches, photoelectric switches or inductive proximityswitches. If, depending upon their width, the originals are introducedon the right-hand or left-hand guide strip of the feed table, theapparatus includes two first, second and third switching elements.

In one arrangement in accordance with the invention, each step-by-stepswitching system comprises a plurality of pairs of contacts and acontact wiper which, as soon as an original actuates the switchingelement associated with the particular step-by-step switching system,passes to the next pair of contacts. In order to store the signalsrelating to two originals and obtained on the basis of the measuredtranslucency and later to' interrogate these signals for the purpose ofcontrolling the speed of the driving motor, each of the step-by-stepswitching systems must contain three pairs of contacts if the thirdswitching element is disposed downstream of the copying station and thestored value relating to this original is cancelled upon actuation ofthe switching element by the trailing edge of the original. If however,the third switching element is disposed upstream of the copying stationand the value associated with the preceding original is cancelled uponactuation by the leading edge of the original, then at least four pairsof contacts are required. For the purpose of storing the signal relatingto each further original, the step-by-step switching systems must eachcomprise an additional pair of contacts. When the storage meanscomprises capacitors, the same applies as regards the number ofcapacitors.

When the storage means comprises capacitors and when the third switchingelement is disposed upstream of the copying station, then according tothe invention, the capacitors are connected to the pairs of contacts inthe step-by-step switching systems in the following way: each pair ofcontacts in the three step-by-step switching systems is connected to acapacitor, each capacitor being connected to the same pair of contactsin each of the first and second step-by-step switching systems, but tothe next pair of contacts in the third step-by-step switching system.If, for example, the first capacitor of the storage means is connectedto the first pair of contacts in the first step-by-step switchingsystem, then it is connected to the first pair of contacts in the secondstep-by-step switching system and to the second pair of contacts in thethird step-by-step switching system. If the third switching element isdisposed downstream of the copying station, then the capacitors areconnected to the same pair of contacts in each of all three step-bystepswitching systems.

In the initial position, the contact wipers of the three step-by-stepswitching systems connect in each of these systems the same pair ofcontacts, e.g. the first of contacts in each case. If for some reason,e.g. interference pulses occurring when the voltage drops, thissynchronous switching of the three step-by-step switching systems isinterfered with, then a device, described in detail hereinafter, issupplied for re-establishing synchronous switching by hand.

According to the invention, the storage means in all the arrangementsmay comprise an analogue-digital flip-flop circuit instead ofcapacitors. In contrast to capacitors, this flip-flop circuit offers theadvantage that the stored signals can be kept constant over a longperiod.

In a preferred arrangement, the second switching element in the path oftravel of the original takes over the function of the third switchingelement, so that the latter can be dispensed with.

When the second switching element is actuated by the leading edge of theoriginal, the signal relating to this original is interrogated while atthe same time the signal relating to the preceding original is cancelledin the storage means. Furthermore, in this arrangement the second andthird step-by-step switching systems are combined to form one system.This step-by-step switching system contains at least four contacts forinterrogation of the stored signals and at least four. contacts forcancellation of the stored signals. Also incorporated in thestep-by-step switching system are two contact wipers which aremechanically interconnected but electrically separated from each other.In such an arrangement, one of the contact wipers associated with thecontacts for interrogating the signals, whereas the second contact wiperis associated with the contacts for cancellation of the signals. Whenthe second switching element is actuated by the leading edge of theoriginal, both contact wipers are shifted to an extent equal to oneswitching period of the next contact so that at the same time the storedsignal relating to the original is interrogated and the stored signalrelating to the preceding original is cancelled.

In this preferred arrangement, the storage means comprises at least fourcapacitors, and the first step-bystep switching system at least fourpairs of contacts. The storage means and the two step-by-step switchingsystems are connected in the following manner: each pair of contacts ofthe first step-by-step switching system and each contact forinterrogating and cancelling of the second step-by-step switching systemare connected to a capacitor. Each capacitor is connected to the pair ofcontacts of the first step-by-step switching system, and in the secondstep-by-step switching system to the contact for the interrogation thatcorresponds to the pair of contacts, but to the next contact for thecancellation. In the initial position, the contact wiper of the firststep-by-step switching system bears on that pair of contacts thatcorresponds to the contacts on which the contact wipers of the secondstep-by-step switching system bear.

When an original is introducedinto the copying machine, it actuates thefirst switching element which due to a brief electrical pulse, switcheson a first step-bystep switching system and also connects thephotosensitive measuring unit to the storage means through the firststep-by-step switching system. Since the connection due to the pulse isvery brief only, it is established through a time-delay unit for alonger period in order to determine the translucency of a portion of theoriginal and thus to increase the likelihood of the translucencymeasurement being carried out on a zone carrying no written matter. Thetime during which the connection is established must be such that forthe highest speed of travel through the copying station and for theshortest size of original, the original covers the photosensitivemeasuring unit during this time. A disadvantage in this translucencymeasurement is that when the originals are long and the speed of travelthrough the copying station is low, only a portion of the original isused for the measurement. In order considerably to reduce the likelihoodof the photosensitive measuring unit being covered by a written strokeduring the measurements, it is advantageous to fix a time during whichthe connection is established not by means of a timedelay unit but bythe length of the original.

For this reason a further switching element is provided in the path oftravel of the original upstream of the photosensitive measuring unit,which switching unit, when actuated by the trailing edge of theoriginal, breaks the connection between the photosensitive measuringunit and the storage means that will have been established when thefirst switching means was actuated by the leading edge of the original.The connection remains established as long as the two switching elementsare covered by the original.

The stored signal relating to an original is interrogated when thesecond step-by-step switching system is switched on. The signal ispassed through an amplifier, e.g. a transistor or an electronic valve,to a device, i.e. a regulator,- which regulates the speed of revolutionof the driving motor and thus the speed of travel of the original. Asignal can be cancelled for example by short-circuiting thecorresponding capacitor by way of a resistor.

When a succeeding original is fed into the copying machine, it firsttravels at the speed determined by the translucency'of the precedingoriginal, until its leading edge actuates the second switching elementand the speed of the driving motor is controlled in dependence upon thetranslucency of the succeeding original. This is disadvantageous whenthe translucency of the preceding original was low and the speed oftravel is correspondingly low. It is therefore advantageous to provide atime-delay unit controllable by the second switching element, whichtime-delay unit switches the driving motor to a pre-set idling speedwhen the original leaves the exposure station.

Instead of a time-delay unit controllable by the second switchingelement, it is possible to fix behind the copying cylinder a scanningdevice which switches the driving motor to a pre-set idling speed whenactuated by the emerging original.

When an original having very low translucency is fed into the copyingmachine and when accordingly a very low speed of travel is required, itmay happen, depending upon the characteristics of the regulator, thatthe driving motor will stop. To prevent this, a voltage, whichcorresponds to the lowest speed at which the driving motor continues toturn, is always applied to the regulator. Then, if an original havingvery low translucency is fed into the copying machine and, as a resultof this measured translucency, a voltage lower than the minimumcontinuously applied to the regulator is passed to the latter when thesignal is interrogated, the driving motor continues to turn at a speedcorresponding to this minimum voltage. A time-consuming stoppage is thusavoided. In this arrangement also, the driving motor can be switched toa pre-set idling speed.

It is advantageous to insert in the beam of light used for measuring thetranslucency, filters which render effective that light-wave range inwhich the copying material is photosensitive. The filters may bearranged in the beam in front of the original, but preferably behind itand in front of the photosensitive measuring unit.

In accordance with a further feature of the invention, a dispersion filmis inserted between the original and the light source in order to smoothout a great differing degree of dispersion in originals of differingtranslucency. Thus, a better correlation between the measuredtranslucency values and the speed of travel through the copying stationcan be achieved by means of the dispersion films.

For measuring the translucency, use is preferably made of the light fromthe light source employed for copying, so that any fluctuations in theemission of light from the copying light source can be taken intoaccount. The light from the copying light source can be conveyed to thephotosensitive measuring unit and the aid of mirrors, metal tubes, or,preferably, UV-lightconducting fiber optics.

According to the invention, the apparatus may be calibrated bydetermining the speeds of travel through the copying station and thetranslucency values for a series of originals of differenttranslucencies. In accordance with the values obtained, the passagethrough zero and the amplification may be so adjusted at the amplifierby means of a potentiometer that for each individual value fortranslucency a corresponding voltage is applied to the regulator, thisvoltage in turn providing the correct speed of the drivng motor and thusthe correct speed of travel for each original. The adjustment of thegain and passage through zero of the amplifier is not only important asregards calibration of the apparatus, but also for adapting theapparatus to suit the particular photosensitivity of the copyingmaterial used. Some copying materials used in copying machines have verydiffering photosensitivities. Furthermore, the photosensitivity of oneand the same copying material changes after a fairly lengthy storageperiod. However, in order to obtain copies with the correct background,the gain and passage through zero of the amplifier are correspondinglyadjusted. Thus the background can be adapted to suit the particularoriginal, depending upon whether the drawing was made in pencil or ink.

If necessary, the automatic control of speed through the copying stationcan be cut off by a manuallyoperated switching means, and a manuallyregulatable voltage applied to the regulator.

The invention is further illustrated by way of example in theaccompanying drawings, in which:

FIG. 1 is a block circuit diagram in the case of a first embodiment ofcopying machine,

FIG. 2 is a diagrammatic plan view of the path of travel of originalsupstream of the copying station, in the case of a second embodiment,

FIG. 3 is a block circuit diagram in the case second embodiment andFIGS. 4 and 5 are detailed circuit diagrams of the storage means and thestep-by-step switching systems for the first and second embodimentsrespectively.

Referring to the drawings, depending upon whether an original 1 having awidth a an original 2 having a width a or an original 3 having a width ais fed into the copying machine, a corresponding one of three webs ofcopying material, provided in rolls 4, Sand 6 respectively, is selected(see FIG. 2). An original 1 having a width a, is fed into the. machinealong a left-hand guide strip of a feed table (not shown in thedrawing), an original 2 having a width a, along a correspondingright-hand guide strip, and an original 3 having a width a can be guidedoptionally on the left or right.

On its way to a copying station 7, an original 1, 2 or 3 passes at leastone of two photosensitive measuring units 8 and 8 which consist of thephotosensitive elements 8a to 8e and 8'a to 8'e respectively. At thispoint, light from a copying light source provided in the machine passesthrough the original 1, 2 or 3, this light or the passing through thefilters 9a to 9e and 9'a to 9'e respectively, and striking thephotosensitive elements 8a to Sc and 8'a to 8'a respectively, whichmeasure the transluce'ncy'of the original 1, 2 or 3 (see FIG. 1). By wayof amplifiers 10a to 10a and 10'a to l0'e respectively, the signals sentby the photosensitive elements 8a to 8e and 8'a to 8'2 respectively andbased on the measured translucency are passed to the discriminators 11and 11' respectively. The discriminator 11 and 11' selects a signal thatcorresponds to the greatest translucency.

When an original 1 having a width a, is fed into the copying machine,its translucency is measured by the photo-sensitive measuring unit 8since a switch S, which establishes connection between thephotosensitive measuring units 8 and 8' and the remaining part of themeasuring system normally bears against a contact 12 see FIGS. 1, 3 and4 When however, an original 2 having a width a is fed into the copyingmachine, then in the course of its travel it actuates a switch S which,as long as it is in contact with the original 2, applies the switch S toa contact 12' through a reversing unit 13, so that the photosensitivemeasuring unit 8' measures the translucency. The same occurs when anoriginal 3 having a width a is introduced on the righthand side of thefeed table. If it is introduced on the left-hand side, then themeasuring unit 8 only measures when the original 3 is so wide that italso actuates the switch S during the course of its travel.

Also disposed in the path of travel of the originals .1, 2 and 3 are twofirst switching elements 8 and S located to the rear of thephotosensitive measuring units 8 and 8'. At least one of these switchingelements S and S is actuated by the original 1, 2 and 3 on its way tothe copying station 7, and as soon as the original covers all thephotosensitive elements 8a to 8e and/or 8'a to 8e of the photosensitivemeasuring units 8 and 8 respectively. As soon as at least one of theswitching elements S and S is actuated, by way of an electronic switch14a, a brief electrical pulse is emitted which causes a contact wiper16a in a first step-by-step switching system 15a (for a storage means18) to move, to an extent equal to a switching period, to an adjacentpair of contacts a, b, c or d, and also closes, by way of a time-delayunit 17, a normally open switch S for a specific period (see FIG. 1).Thus, by way of the stepby-step measuring system 15a, connection isestablished between one of the photosensitive measuring units 8 and 8'and the storage means 18. By way of the discriminator 11 or 11 thesignal corresponding to the greatest degree of translucency measured bythe photo-' sensitive elements 8a to 8e or 8'a to 8'e respectively isstored in one of the capacitors C C C and C of the storage means 18(FIG. 4).

Downstream of the switching element 8;, and S, in the path of travel ofthe originals l, 2 and 3 are disposed two second switching elements Sand 8,. At least one of these switching elements S and S is actuated bythe original 1, 2 or 3 on its way to the copying station 7,'so that theswitching elements 8., and/or S-, release a brief electrical pulse byway of an electronic switch 14b, which pulse causes a contact wiper 16bin a second step-by-step switching system 15b (for the interrogation) tomove to an extent equal to a switching period to an adjacent pair ofcontacts a, b', c or d (see FIG. 4). This causes one of the capacitors CC C and C to be connected to an amplifier 19, and in fact that one of ofthe capacitors C C C or C, that is connected to the pair of contacts a,b, c or d reached by the contact wiper 16b, is connected to theamplifier 19. The signal stored in the particular capacitor C C C or Cis thus passed by way of the amplifier 19 to a regulator 20 whichregulates the speed of revolution of a driving motor 21 and thus thespeed of travel of the original 1, 2 or 3.

Finally, in the first embodiment (see FIG. 1), two third switchingelements S and 8,, (not shown in FIG. 2) are disposed in the path oftravel of the original I, 2 or 3 upstream of the copying station 7. Atleast one of these switching elements S and S is actuated by theoriginal 1, 2 or 3 so that the switching elements S or S release a briefelectrical pulse by way of an electronic switch 14c, which pulse causesa contact wiper 166 in a third step-by-step switching system 150 for thecancellation to move to an extent equal to a switching period to anadjacent pair of contacts a, b", c" or d" (see FIG. 4). This establishesconnection between one of the capacitors C C C or C, and a groundedresistor 22, and in fact that one of the capacitors C C C or C, which isconnected to the pair of contacts a", b, c" or d" reached by the contactwiper 160, is connected to the resistor 22 and thus cancels its storedsignal.

The switching elements and S can be connected either in series or inparallel. In the first case they are normally closed see FIG. 1 or 4and, when actuated by an original 1, 2 or 3, they are opened. Theopening of one or both of the switching elements 8;, and S. causes therelease of the pulse at the electronic switch 14a. If the switchingelements are connected in parallel, they are normally opened (not shownin the drawings), and when actuated by an original 1, 2 or 3, they areclosed. The closing of one or both of the switching elements S and Scauses the release of the pulse at the electronic switch 14a. The sameapplies in the case of the switching elements S 8 and S and 8,.

Each pair of contacts a to d, a to d and a" to d" in the threestep-by-step switching systems 15a, 15b and 15c is connected to one ofthe capacitors C C C and C Each capacitor C C C and C is connected toeach like pair of contacts a to d and a to d of the first and secondstep-by-step switching systems 15a and 15b, for example C to a and a, orC to b and b, but to the next pair of contacts b" to a" of the thirdstepby-step switching system 15c, for example C to b" or C, to c" (seeFIG. 4).

The contact wipers 16a, 16b and 160 must be moved into the startingposition in synchronism. When the contact wiper 16a in the step-by-stepswitching system 15b, for example, connects the pair of contacts a, thecontact wiper 16b in the step-by-step switching system 15b must connectthe pair of contacts a and the contact wiper 160 in the step-by-stepswitching system 150 must connect the pair of contacts a". Ifsynchronous actuation of the three step-by-step switching systems 15a,15b, and 15c is disturbed, for example by interference pulses during avoltage drop, then synchronism can be re-established manually. For thispurpose, in each of the three step-by-step switching systems 15a, 15band 15c, each one of the pairs of contacts a to d, a to d and a" to d isconnected to a lamp L L and L respectively. The contacts that areconnected to the lamps are the same in the three step-by-step switchingsystems 15a 15b and 15c.

In FIG. 4, for example, the contacts d, d and d" are connected to thelamps L L and L respectively. Also provided is a manually operableswitching arrangement S which when actuated firstly prevents connectionbetween the photo-sensitive measuring units 8 and 8' and thestep-by-step switching system 15a, secondly shortcircuits the capacitorsC, to C, of the storage means 18 so that one pole of a voltage source isapplied to each pair of contacts a to d, a to d and a" to d" of thethree step-by-step switching systems lSa, 15b, and 15c, and thirdlyapplies the other pole of the voltage source to each of the lamps L Land L With the aid of manually operable setting keys S S and S thecontact wipers 16a, 16b and 1160 respectively can be each individuallydisplaced by way of the electronic switches Ma 14b and 140. When, forexample, the contact wiper 16a is displaced with the aid of the settingkey S by way of the electronic switch 14a, then the circuit is closedand the lamp L lights up as soon as the contact wiper 16a has reachedthe pair of contacts 11. The same applies in the case of the contactwipers 16b and 160. The three step-by-step switching systems aresynchronously actuated as soon as all three lamps L L and L light up.

In the second embodiment see FIGS. 2, 3 and 5), the functions of thethird switching elements 8,; and S are taken over by the secondswitching elements 8.; and S The second and third step-by-step switchingsystems 15b and are combined to form one system 15d. If an original ll,2 or 3 actuates one of the switches S and s and a brief electrical pulseis thus released by way of an electronic switch 14d, then the contactwipers 16d and 16d in the second step-by-step switching system 15d areeach switched to an extent corresponding to a switching period to thenext contact e,f, g or h, and e, fg, or h respectively. Thus,interrogation of the stored signals relating to an original 1, 2 or 3 isachieved for controlling the speed of revolution of the driving motor211, and the stored signal relating to the preceding original 1, 2 or 3is cancelled through the resistor 22.

Each of the capacitors C C C and C is connected to a pair of contacts inthe first step-by-nep switching system Ma and to a contact forinterrogation and a contact for cancellation in the second step-by-stepswitching system 1501, for example capacitor C is connected to the pairof contacts a, the contact e and the contact f and capacitor 0 isconnected to the pair of contacts b, the contact f and the contact g.

In order to determine, by the length of the original, the time duringwhich the photosensitive measuring unit 8 or 8' is connected to thestorage means 18 through the first step-by-step switching system 15a,switching elements S and S (see FIG. 2) are disposed in the path oftravel of the original upstream of the photosensitive measuring units 8and 8. The switching elements S and S are connected by an AND gate 23,and the switching elements 8., and S by an AND gate 24 (see FIG. 5).Each AND gate 23 and 24 then only passes a signal at its output when asignal is simultaneously sent to its two inputs. Thus, a signal is onlypassed on if the switching elements S and S or 8,, and S aresimultaneously actuated by the original. Connected downstream of the twoAND gates 23 and 24 is an OR gate 25. This OR gate passes a signal tothe switch S5 as soon as one of the two AND gates 23 or 24 sends asignal. The switch S is then closed for this period. The means foractuating the switching elements 8,, S S and 5,, through the AND gates23 and 24 and the OR gate 25 is designated as a measured time unit 26 inthe block circuit diagram of FIG. 3.

As can be seen from FIG. 3, the second switching elements 8,, and S, areconnected to an OR gate 27 which, as soon as one of the two switchingelements S and S is actuated by the leading edge of the original, sendsa pulse to a time-delay unit 28. A switch S is thereby immediatelyapplied to its contact 29. The switch S is disposed between theamplifier l9 and the regulator 20. As soon as the trailing edge of theoriginal clears the switching element S and/or 5, the unit 26 switchesin a delay period at the expiration of which the switch S is lifted fromthe contact 29 and applied to its contact 29, so that the regulator 20is connected to a mains component 30. The voltage now applied to theregulator 20 can be pre-set and advantageously so selected that thedriving motor 21 turns at its highest speed.

As also shown in FIG. 3, voltage is applied to the regulator 20 througha minimum-value setting means 3ll, when switch S bears against itscontact 29. The minimum-value setting means 31 may for example comprisea potentiometer in combination with diodes by means of which thatvoltage is applied to the regulator 20 that corresponds to the lowestspeed at which the driving motor 21 is able to turn.

The mode of operation will now be explained by reference to the secondembodiment and assuming two originals to be fed into the copying machineone after the other. The switch S bears on the contact 29' and theregulator 20 is thus connected to the mains component 30. The drivingmotor 21 is turning-at idling speed which corresponds to the voltageapplied to the regulator 20 (see FlG. 3). As seen in FIG. 5, thecapacitor C is discharged through the resistor 22. The signal relatingto the last original is still stored in the capacitor C,. If now, forexample, an original 1 is fed into the copying machine, it firstactuates the switching element S Since this switching element isconnected to the switching element 8;, through the AND gate 23, and theoriginal has not yet reached S the switch S remains open. The original 1passes over the photosensitive measuring unit 8. When the switchingelement 5;, is actuated by the leading edge of the original, switchingelement 8;, is changed over from its contact 32 to its contact 32. Whenthis happens a pluse is sent to the electronic switch 14a, so that thecontact wiper 16a is moved from the pair of contacts a to the pair ofcontacts b. Since the switching elements 5,, bears on its contact 32 andthe switching element 8,, is closed, the AND gate 23 sends the signal tothe OR gate 25 and the switch S is thus closed. The photosensitivemeasuring unit 8 is connected through the step-by-step switching systema to the capacitor C of the storage means 18. The capacitor C is chargedto an extent corresponding to the translucency of the original 1measured on the photosensitive measuring unit 8. As soon as the trailingedge of the original clears the switching element S the latter is openedagain, and since a signal is now still present only at one input of theAND gate 23, the switch S is opened. When the trailing edge of theoriginal clears the switching element S this is again applied to thecontact 32'.

In the meantime, a second original, the original 2, is fed intothecopying machine. It actuates the switching element S passes over thephotosensitive measuring unit 8 and actuates the switch S As describedabove, the switch S normally applied to the contact 112 is thus liftedfrom this contact and applied to the contact 12'. When the leading edgeof the original reaches the switching element S the contact wiper 16amoves from the pair of contacts b to the pair of contacts 0, and sincethe switching element 8., now lies on its contact 33, and switchingelement 8, is at the same time closed, the switch S is closed. Thecapacitor C is charged to an extent corresponding to the translucency ofthe original 2. As soon as the trailing edge of the original clears theswitching element S the switch S is opened again. The introduction of athird original is not possible since the capacitor C is grounded throughthe contact wiper 16d. To enable a third original to be fed in and thesignal relating to it to be stored, a fifth capacitor would have to beprovided, and also a fifth pair of contacts in the step-by-stepswitching system 150, and a fifth contact each, for interrogation andcan'- cellation, in the step-by-step switching system 1511.

When the original 1 reaches the switching element S the latter ischanged over from its contact 34' to its contact 34. This causes a briefpulse to be released at the electronic switch Md, which pulses switchesthe contact wiper 16d in the step-by-step switching system 15d from thecontact e to the contact f, and switches the contact wiper 116dmechanically connected to the contact wiper Mid, from the contact e tothe contact f. The switching of switching elements over to its contact341 also results in the actuation, by way of the OR gate 27, of thetime-delay unit 28 which immediately applies the switch S to the contact29. The signal relating to the original l and stored in the capacitor Cis thereby applied by way of the amplifier 19 to the regulator 20 whichappropriately regulates the speed of revolution of the drive motor 21.If the value of the voltage deriving from the amplifier 119 is lowerthan the voltage applied to the regulator through the minimumvaluesetting means 31, the driving motor continues to run at a speed whichcorresponds to the voltage deriving from the minimum-value setting means31. If the level of the voltage deriving from the amplifier 19 is higherthan that of the minimum-value setting means 31, then the driving motor21 turns at a speed which corresponds to the level of the voltagederiving from the amplifier 19.

Switching of the contact wiper 36d discharges the capacitor C throughthe resistor 22. The capacitor C is free to store the signal relating toa fresh original which now may be introduced.

When the trailing edge of the original l leaves the switching element Sthe latter is changed back to its contact 34' so that the time-delayunit 28 switches in a specific delay period upon the expiration of whichswitch S is applied to its contact 29. The voltage of the mainscomponent 3th is thus applied to the regulator. The delay period is suchthat upon its expiration the original ll will have left the copyingstation 7.

The original 2 is still located between the machine feed point and thecopying station 7. When it reaches the switching element S the latter isapplied to its contact 35, and thus the switch S is again applied to thecontact 22. At the same time, the contact wipers lldd and Md in thesecond step-by-step switching system 1150! are each moved forward to anextent corresponding to a switching period to the next contact, i.e.

to the contacts g and g. The signal relating to the original 2 is thusinterrogated by the capacitor C, so that the original 2 enters thecopying station 7 at a speed of travel corresponding to itstranslucency. At the same time, the signal relating to the origianl 1and stored in the capacitor C is cancelled; the capacitor C is free forstoring a signal relating to a further original. When the switch S iscleared by the trailing edge of the original 2, the switch S is againapplied to its contact 12. When the switching element S is cleared, theswitch S is again applied to its contact 29' after a specific time lag.The driving motor 21 again turns at its idling speed.

As regards synchronization of the step-by-step switching systems a and15d, the same applies as in the first embodiment. Since the contactwipers 16d and 16d are mechanically interconnected, it suffices simplyto connect one lamp L to the contact h, and it is only necessary to haveone manually operable switch S with which the contact wipers 16d and 16deach can be moved forward to an extent equal to the switching period. Assoon as lamps L and L light up together, the two step-by-step switchingsystems 15a and 15d are actuated in synchronism.

It will be obvious to those skilled in the art that many modificationsmay be made within the scope of the present invention without departingfrom the spirit thereof, and the invention includes all suchmodifications.

What is claimed is:

1. An apparatus for automatically controlling the speed at which asucceeding original and copying material pass through the copying zoneof a continuously operable copying machine having a motor drive fororiginals and copying material, said apparatus comprising, successivelydisposed in the path of travel of the said original upstream of thecopying zone:

at least one photosensitive measuring unit means, ar-

ranged to measure the translucency of the said original,

at least one first switching element means which is adapted foractuation by the leading edge of the said original and which when soactuated:

a. switches on a first step-by-step switching system,

and

b. connects the photosensitive measuring unit means to a storage unitfor a brief period by way of the said step-by-step switching systemwhereby the signal derived from said measuring unit means is stored,

at least one second switching element means which is adapted foractuation by the leading edge of the said original and which when soactuated switches on a second step-by-step switching system whereby thestores signal is passed through an amplifier to a device for controllingthe speed of the motor during the passage of the said original andcopying material through the copying zone, and

at least one third switching element means which is adapted foractuation by the leading edge of the said original and which when soactuated switches on a third step-by-step switching system, whereby astored signal relating to the preceding original is cancelled.

2. Anapparatus as claimed in claim 1, in which the storage unitcomprises at least four capacitors and each of the three step-by-stepswitching systems comprises a series of at least four pairs of contactswhich are each connected to one of the capacitors, each capacitor beingconnected to those pairs of contacts of the first and secondstep-by-step switching systems which are in the same positions in thecorresponding series, but to the next pair of contacts of the series inthe case of the third step-by-step switching system.

3. An apparatus as claimed in claim 1, in which, in the initial positionin each step-by-step switching system, contact wipers in the threestep-by-step switching systems connect pairs of contacts which are inthe same positions in corresponding series.

4. An apparatus as claimed in claim 3, in which, for the purpose ofsynchronizing the three step-by-step switching systems, one of the pairsof contacts in each of said systems is connected respectively to one ofthree lamps, the pairs of contacts connected to the lamps being in thesame positions in their corresponding series, and a manually operableswitching means is present which is so arranged that when actuated itprevents connection between the photosensitive measuring unit means andthe storage means,

short-circuit the capacitors of the storage means, so that one pole of avoltage source is applied to each pair of contacts of the threestep-by-step switching systems, and

applies to other pole of the voltage source to each of the lamps, andmanually operable setting keys are provided by means of which thecontact wipers are individually displaceable to their alternativecontacts.

5. An apparatus for automatically controlling the speed at which anoriginal and copying material pass through the copying zone of a copyingmachine having a motor drive for original and copying material, saidapparatus comprising, successively disposed in the path of travel of theoriginal upstream of the copying zone:

at least one photosensitive measuring unit means, ar-

ranged to measure the translucency of the original, at least one firstswitching element means which is adapted for actuation by the leadingedge of the original and which when so actuated: a. switches on afirst'step-by-step switching system,

and. i 7 b. connects the photosensitive measuring unit means to astorage unit for a brief period by way of the said step-by-stepswitching system whereby the signal derived from said measuring unitmeans is stored, at least one second switching element means which isadapted for actuation by the leading edge of the original and which whenso actuated switches on a second step-by-step switching system wherebythe stored signal is passed through an amplifier to a device forcontrolling the speed of the motor during the passage of original andcopying material through the copying zone, and further comprising athird switching element means disposed in the path of travel of theoriginal downstream of the copying zone, which latter switching elementmeans is adapted for actuation by the trailing edge of the original andwhich when so actuated switches on a third step-by-step switching systemwhereby the stored signal is cancelled.

6. An apparatus as claimed in claim 5 in which, in the initial positionin each step-by-step switching system, contact wipers in the threestep-by-step switching systerns connect pairs of contacts which are inthe same positions in corresponding series.

7. An apparatus as claimed in claim 6, in which, for the purpose ofsynchronizing the three step-by-step switching systems, one of the pairsof contacts in each of said systems is connected respectively to one ofthree lamps, the pairs of contacts connected to the lamps being in thesame positions in their corresponding series, and a manually operableswitching means is present which is so arranged that when actuated itprevents connection between the photosensitive measuring unit means andthe storage means,

- short-circuits the capacitors of the storage means, so that one poleof a voltage source is applied to each pair of contacts of the threestep-by-step switching systems, and

applies to other pole of the voltage source to each of the lamps, andmanually operable setting keys are provided by means of which thecontact wipers are individually displaceable to their alternativecontacts.

8. An apparatus as claimed in claim 5, in which the storage unitcomprises at least three capacitors and each of the three step-by-stepswitching systems comprises a series of at least three pairs ofcontacts, each pair of contacts being connected to one of the capacitorsand each capacitor being connected to those pairs of contacts in thethree step-by-step switching systems which are in the same positions inthe different series.

9. An apparatus for automatically controlling the speed at which asucceeding original and copying material pass through the copying zoneof a continuously operable copying machine having a motor drive fororiginals and copying material, said apparatus comprising, successivelydisposed in the path of travel of the said original upstream of thecopying zone:

at least one photosensitive measuring unit means, ar-

ranged to measure the translucency of the said original,

at least one first switching element means which is adapted foractuation by the leading edge of the said original and when so actuatd:

a. switches on a first step-by-step switching system and b. connects thephotosensitive measuring unit' means to a storage unit for a briefperiod by way of the said step-by-step switching system whereby thesignal derived from said measuring unit is stored,

at least one second switching element means which is adapted foractuation by the leading edge of the said original and which when soactuated switches on a second step-by-step switching system whereby a.the stored signal is passed through an amplifier to a device forcontrolling the speed of the motor during the passage of the saidoriginal and copying material through the copying zone, and

b. a stored signal relating to the preceding original is cancelled.

10. An apparatus as claimed in claim 9, in which the storage unitcomprises an analogue-digital controlled flip-flop circuit.

11. An apparatus as claimed in claim 9, in which at least one furtherswitching element is disposed in the path of travel of the originalupstream of the photosensitive measuring unit, which switching elementis adapted to disconnect the photosensitive measuring unit from thestorage unit when the trailing edge of the original passes said furtherswitching element or elements.

12. An apparatus as claimed in claim 9, including means for continuouslyapplying a voltage corresponding to the lowest speed of the motor to themeans for controlling the speed of this motor.

13. An apparatus as claimed in claim 9, including a time-delay unitwhich is controllable by the second switching element and by means ofwhich the driving motor can be switched to a pre-set idling speed.

14. An apparatus as claimed in claim 9, in which the photosensitivemeasuring unit means comprises a plurality of photosensitive elementsdistributed across the path of the original and including adiscriminator connected between the photosensitive measuring unit andthe storage unit for the purpose of selecting that signal correspondingto the greatest translucency of the original.

15. An apparatus as claimed in claim 14, in which the photosensitiveelements are in staggered relation to one another parallel to thedirection of movement of the original.

16. An apparatus as claimed in claim 9, including filters disposed inthe path of a beam of light used for measuring the translucency of theoriginal.

17. An apparatus as claimed in claim 9, including a dispersion filmlocated between the light source used for measuring the translucency andthe path of the original.

18. An apparatus as claimed in claim 9, in which a copying light sourceis arranged for use as the light source for measuring translucency.

19. An apparatus as claimed in claim 18, including UV-light-conductingfiber optics for directing the light.

20. An apparatus as claimed in claim 9, including potentiometers forsuiting the particular sensitivity of the copying material and forcalibrating the control apparatus, whereby the passage through zero andalso the gain of the amplifier can be adjusted.

21. An apparatus as claimed in claim 9, in which the storage unitcomprises at least four capacitors, the first step-by-step' switchingsystem comprises a series of at least four pairs of contacts, and thesecond step-by-step switching system comprises a series of at least fourcontacts for interrogation and a series of at least four contacts forcancellation and also two contact wipers which are mechanicallyinterconnected but electrically separate from one another.

22. An apparatus as claimed in claim 21, in which each pair of contactsof the first series and each contact of a series for interrogation andof a series for cancellation are connected to one of the capacitors,each capacitor being connected to that pair of contacts of the firstseries and to that contact for interrogation which are in the samepositions in the series, but to the next contact in the said series forcancellation.

23. An apparatus as claimed in claim 9, in which, in the initialposition, a contact wiper of the first step-bystep switching systembears on that one of the pairs of contacts of the system thatcorresponds to the contacts of the second step-by-step switching systemon which contact wipers of the second step-by-step switching systembear.

24. An apparatus as claimed in claim 23, in which for the purpose ofsynchronizing the two step-by-step switching systems, one of the pairsof contacts in the pair of contacts of the first step-by-step switchingsystem and to each contact of the second step-bystep switching system,and applies the other pole of the voltage source to each of the twolamps, and including manually operable setting keys, by means of whichthe contact wipers in the two step-by-step switching systems aredisplaceable to their alternative COIltflCtS.

1. An apparatus for automatically controlling the speed at which asucceeding original and copying material pass through the copying zoneof a continuously operable copying machine having a motor drive fororiginals and copying material, said apparatus comprising, successivelydisposed in the path of travel of the said original upstream of thecopying zone: at least one photosensitive measuring unit means, arrangedto measure the translucency of the said original, at least one firstswitching element means which is adaPted for actuation by the leadingedge of the said original and which when so actuated: a. switches on afirst step-by-step switching system, and b. connects the photosensitivemeasuring unit means to a storage unit for a brief period by way of thesaid step-bystep switching system whereby the signal derived from saidmeasuring unit means is stored, at least one second switching elementmeans which is adapted for actuation by the leading edge of the saidoriginal and which when so actuated switches on a second step-by-stepswitching system whereby the stores signal is passed through anamplifier to a device for controlling the speed of the motor during thepassage of the said original and copying material through the copyingzone, and at least one third switching element means which is adaptedfor actuation by the leading edge of the said original and which when soactuated switches on a third step-by-step switching system, whereby astored signal relating to the preceding original is cancelled.
 2. Anapparatus as claimed in claim 1, in which the storage unit comprises atleast four capacitors and each of the three step-by-step switchingsystems comprises a series of at least four pairs of contacts which areeach connected to one of the capacitors, each capacitor being connectedto those pairs of contacts of the first and second step-by-stepswitching systems which are in the same positions in the correspondingseries, but to the next pair of contacts of the series in the case ofthe third step-by-step switching system.
 3. An apparatus as claimed inclaim 1, in which, in the initial position in each step-by-stepswitching system, contact wipers in the three step-by-step switchingsystems connect pairs of contacts which are in the same positions incorresponding series.
 4. An apparatus as claimed in claim 3, in which,for the purpose of synchronizing the three step-by-step switchingsystems, one of the pairs of contacts in each of said systems isconnected respectively to one of three lamps, the pairs of contactsconnected to the lamps being in the same positions in theircorresponding series, and a manually operable switching means is presentwhich is so arranged that when actuated it prevents connection betweenthe photosensitive measuring unit means and the storage means,short-circuit the capacitors of the storage means, so that one pole of avoltage source is applied to each pair of contacts of the threestep-by-step switching systems, and applies to other pole of the voltagesource to each of the lamps, and manually operable setting keys areprovided by means of which the contact wipers are individuallydisplaceable to their alternative contacts.
 5. An apparatus forautomatically controlling the speed at which an original and copyingmaterial pass through the copying zone of a copying machine having amotor drive for original and copying material, said apparatuscomprising, successively disposed in the path of travel of the originalupstream of the copying zone: at least one photosensitive measuring unitmeans, arranged to measure the translucency of the original, at leastone first switching element means which is adapted for actuation by theleading edge of the original and which when so actuated: a. switches ona first step-by-step switching system, and b. connects thephotosensitive measuring unit means to a storage unit for a brief periodby way of the said step-by-step switching system whereby the signalderived from said measuring unit means is stored, at least one secondswitching element means which is adapted for actuation by the leadingedge of the original and which when so actuated switches on a secondstep-by-step switching system whereby the stored signal is passedthrough an amplifier to a device for controlling the speed of the motorduring the passage of original and copying material through the copyingzone, and further comprising a third switching element means disposed inThe path of travel of the original downstream of the copying zone, whichlatter switching element means is adapted for actuation by the trailingedge of the original and which when so actuated switches on a thirdstep-by-step switching system whereby the stored signal is cancelled. 6.An apparatus as claimed in claim 5 in which, in the initial position ineach step-by-step switching system, contact wipers in the threestep-by-step switching systems connect pairs of contacts which are inthe same positions in corresponding series.
 7. An apparatus as claimedin claim 6, in which, for the purpose of synchronizing the threestep-by-step switching systems, one of the pairs of contacts in each ofsaid systems is connected respectively to one of three lamps, the pairsof contacts connected to the lamps being in the same positions in theircorresponding series, and a manually operable switching means is presentwhich is so arranged that when actuated it prevents connection betweenthe photosensitive measuring unit means and the storage means,short-circuits the capacitors of the storage means, so that one pole ofa voltage source is applied to each pair of contacts of the threestep-by-step switching systems, and applies to other pole of the voltagesource to each of the lamps, and manually operable setting keys areprovided by means of which the contact wipers are individuallydisplaceable to their alternative contacts.
 8. An apparatus as claimedin claim 5, in which the storage unit comprises at least threecapacitors and each of the three step-by-step switching systemscomprises a series of at least three pairs of contacts, each pair ofcontacts being connected to one of the capacitors and each capacitorbeing connected to those pairs of contacts in the three step-by-stepswitching systems which are in the same positions in the differentseries.
 9. An apparatus for automatically controlling the speed at whicha succeeding original and copying material pass through the copying zoneof a continuously operable copying machine having a motor drive fororiginals and copying material, said apparatus comprising, successivelydisposed in the path of travel of the said original upstream of thecopying zone: at least one photosensitive measuring unit means, arrangedto measure the translucency of the said original, at least one firstswitching element means which is adapted for actuation by the leadingedge of the said original and when so actuatd: a. switches on a firststep-by-step switching system and b. connects the photosensitivemeasuring unit means to a storage unit for a brief period by way of thesaid step-by-step switching system whereby the signal derived from saidmeasuring unit is stored, at least one second switching element meanswhich is adapted for actuation by the leading edge of the said originaland which when so actuated switches on a second step-by-step switchingsystem whereby a. the stored signal is passed through an amplifier to adevice for controlling the speed of the motor during the passage of thesaid original and copying material through the copying zone, and b. astored signal relating to the preceding original is cancelled.
 10. Anapparatus as claimed in claim 9, in which the storage unit comprises ananalogue-digital controlled flip-flop circuit.
 11. An apparatus asclaimed in claim 9, in which at least one further switching element isdisposed in the path of travel of the original upstream of thephotosensitive measuring unit, which switching element is adapted todisconnect the photosensitive measuring unit from the storage unit whenthe trailing edge of the original passes said further switching elementor elements.
 12. An apparatus as claimed in claim 9, including means forcontinuously applying a voltage corresponding to the lowest speed of themotor to the means for controlling the speed of this motor.
 13. Anapparatus as claimed in claim 9, including a time-Delay unit which iscontrollable by the second switching element and by means of which thedriving motor can be switched to a pre-set idling speed.
 14. Anapparatus as claimed in claim 9, in which the photosensitive measuringunit means comprises a plurality of photosensitive elements distributedacross the path of the original and including a discriminator connectedbetween the photosensitive measuring unit and the storage unit for thepurpose of selecting that signal corresponding to the greatesttranslucency of the original.
 15. An apparatus as claimed in claim 14,in which the photosensitive elements are in staggered relation to oneanother parallel to the direction of movement of the original.
 16. Anapparatus as claimed in claim 9, including filters disposed in the pathof a beam of light used for measuring the translucency of the original.17. An apparatus as claimed in claim 9, including a dispersion filmlocated between the light source used for measuring the translucency andthe path of the original.
 18. An apparatus as claimed in claim 9, inwhich a copying light source is arranged for use as the light source formeasuring translucency.
 19. An apparatus as claimed in claim 18,including UV-light-conducting fiber optics for directing the light. 20.An apparatus as claimed in claim 9, including potentiometers for suitingthe particular sensitivity of the copying material and for calibratingthe control apparatus, whereby the passage through zero and also thegain of the amplifier can be adjusted.
 21. An apparatus as claimed inclaim 9, in which the storage unit comprises at least four capacitors,the first step-by-step switching system comprises a series of at leastfour pairs of contacts, and the second step-by-step switching systemcomprises a series of at least four contacts for interrogation and aseries of at least four contacts for cancellation and also two contactwipers which are mechanically interconnected but electrically separatefrom one another.
 22. An apparatus as claimed in claim 21, in which eachpair of contacts of the first series and each contact of a series forinterrogation and of a series for cancellation are connected to one ofthe capacitors, each capacitor being connected to that pair of contactsof the first series and to that contact for interrogation which are inthe same positions in the series, but to the next contact in the saidseries for cancellation.
 23. An apparatus as claimed in claim 9, inwhich, in the initial position, a contact wiper of the firststep-by-step switching system bears on that one of the pairs of contactsof the system that corresponds to the contacts of the secondstep-by-step switching system on which contact wipers of the secondstep-by-step switching system bear.
 24. An apparatus as claimed in claim23, in which for the purpose of synchronizing the two step-by-stepswitching systems, one of the pairs of contacts in the first system andone of the contacts in the second system are each connected to one oftwo lamps, the pair of contacts of the first system, connected to afirst of these lamps corresponding to the contact of the second systemconnected to the second lamp, and a manually operable switching means isprovided which upon actuation prevents connection between thephotosensitive measuring unit means and the storage means,short-circuits the capacitors of the storage means so that one pole of avoltage source is applied to each pair of contacts of the firststep-by-step switching system and to each contact of the secondstep-by-step switching system, and applies the other pole of the voltagesource to each of the two lamps, and including manually operable settingkeys, by means of which the contact wipers in the two step-by-stepswitching systems are displaceable to their alternative contacts.